Hi, list
This is V3 patch series that provide the ability for each memory cgroup to
have independent dirty/writeback page statistics which can provide
information
for per-cgroup direct reclaim or some.
In the first three prepare patches, we have done some cleanup and reworked
vfs
set page dirty routines to make "modify page info" and "dirty page
accouting" stay
in one function as much as possible for the sake of memcg bigger lock(test
numbers
are in the specific patch). There is no change comparing to V2.
Patch 4/8 and 5/8 are acctually doing memcg dirty and writeback page
accounting.
We change lock orders of mapping->tree_lock and memcg->move_lock to prevent
deadlock. Test numbers of previous version show that there is some
performance
decrease after patching the accouting once memcg is enabled. The reason is
that
if no memcg exists but root_mem_cgroup, all allocated pages are belonging
to root memcg
and they will go through root memcg statistics routines which brings
overheads.
So we do some optimization in patch 6/8 and 7/8: patch 6 chooses to give up
accounting
root memcg stat but changes behavior of memcg_stat_show() instead; patch 7
uses jump
label to disable memcg page stat accounting code when not in use which is
inspired by
a similar optimization from Glauber Costa
(memcg: make it suck faster; https://lkml.org/lkml/2012/9/25/154).
On a 4g memory and 4-core i5 CPU machine, we pushing 1G data through 600M
memcg
(memory.limit_in_bytes=600M, memory.memsw.limit_in_bytes=1500M) by fio:
fio
(ioengine=sync/write/buffered/bs=4k/size=1g/numjobs=2/group_reporting/thread)
Following is performance comparison between before/after the whole series
(test it for 10 times and get the average numbers):
Before:
write: io=2048.0MB, bw=214527KB/s, iops=53631.2 , runt= 9880.1msec
lat (usec): min=1 , max=1685.06K, avg=36.182, stdev=3153.97
After:
write: io=2048.0MB, bw=193069KB/s, iops=48266.6 , runt= 11078.6msec
lat (usec): min=1 , max=1634.26K, avg=40.598, stdev=3135.81
Note that now the impact is little(~1%).
Any comments are welcomed. : )
Change log:
v3 tree_lock and memcg->move_lock
2. performance optimization in 6/8 and 7/8
v2 [email protected] For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: email@kvack.org